1. Field of the Invention
The present invention relates to navigation apparatus, and particularly relates to navigation apparatus using real image data corresponding to an image such as a satellite photograph or an aerial photograph showing the surface of the earth.
2. Description of the Related Art
A navigation apparatus in the related art can display a map on a screen of a display unit on the basis of map data recorded in a DVD-ROM or the like, or can further display the position of the navigation apparatus itself on the map on the basis of position data of its own, so as to navigate a user along a route for a destination.
However, in the navigation apparatus in the related art, the map screen to be displayed is made up from the map data used. Accordingly, there is a problem that it is difficult for the user to catch the current position of the navigation apparatus itself on the map screen or to grasp the real conditions in the periphery of the current position of the navigation apparatus itself.
This is because it is difficult to express the vertical position relationship between roads solidly crossing with each other on the map screen, and in fact there are many roads and buildings not displayed on the map screen.
As one of solutions to such a problem, there has been disclosed an invention in which the current position of the apparatus itself is displayed on an aerial photograph screen made up from aerial photograph data (JP-A-5-113343). With such an aerial photograph screen, it becomes very easy to find a building or the like as a landmark. Thus, it becomes easy to catch the current position of the apparatus itself. In addition, there is an advantage that it can be also made easy to grasp the real conditions of the periphery of the current position of the apparatus itself.
However, by merely displaying an aerial photograph screen in JP-A-5-113343, it is impossible to attain navigation apparatus satisfying a user sufficiently.
For example, the navigation apparatus in the related art is provided with a function of displaying character information of primary place names, building names, or the like, as additional information over the real image on the map screen. It is expected that the character information will be also displayed over the real image such as an aerial photograph in the future.
However, when the character information is displayed over the real image such as an aerial photograph in the same manner as in the related art, there is a fear that it becomes difficult to see the real image (in addition, there is also a fear that the character information becomes inconspicuous). Conceivably, this is because the real image is an aerial photograph or the like showing the real surface of the earth so that the real image may include a place not suitable for displaying the character information or the like over there.